/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.rest.handler.job;

import org.apache.flink.runtime.execution.ExecutionState;
import org.apache.flink.runtime.executiongraph.AccessExecutionGraph;
import org.apache.flink.runtime.executiongraph.AccessExecutionJobVertex;
import org.apache.flink.runtime.executiongraph.AccessExecutionVertex;
import org.apache.flink.runtime.rest.handler.HandlerRequest;
import org.apache.flink.runtime.rest.handler.legacy.ExecutionGraphCache;
import org.apache.flink.runtime.rest.messages.EmptyRequestBody;
import org.apache.flink.runtime.rest.messages.JobIDPathParameter;
import org.apache.flink.runtime.rest.messages.JobVertexIdPathParameter;
import org.apache.flink.runtime.rest.messages.JobVertexMessageParameters;
import org.apache.flink.runtime.rest.messages.MessageHeaders;
import org.apache.flink.runtime.rest.messages.ResponseBody;
import org.apache.flink.runtime.rest.messages.SubtasksTimesInfo;
import org.apache.flink.runtime.taskmanager.TaskManagerLocation;
import org.apache.flink.runtime.webmonitor.RestfulGateway;
import org.apache.flink.runtime.webmonitor.history.ArchivedJson;
import org.apache.flink.runtime.webmonitor.history.OnlyExecutionGraphJsonArchivist;
import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever;
import org.apache.flink.util.CollectionUtil;

import java.io.IOException;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Executor;

/** Request handler for the subtasks times info. */
public class SubtasksTimesHandler
        extends AbstractJobVertexHandler<SubtasksTimesInfo, JobVertexMessageParameters>
        implements OnlyExecutionGraphJsonArchivist {
    public SubtasksTimesHandler(
            GatewayRetriever<? extends RestfulGateway> leaderRetriever,
            Duration timeout,
            Map<String, String> responseHeaders,
            MessageHeaders<EmptyRequestBody, SubtasksTimesInfo, JobVertexMessageParameters>
                    messageHeaders,
            ExecutionGraphCache executionGraphCache,
            Executor executor) {
        super(
                leaderRetriever,
                timeout,
                responseHeaders,
                messageHeaders,
                executionGraphCache,
                executor);
    }

    @Override
    protected SubtasksTimesInfo handleRequest(
            HandlerRequest<EmptyRequestBody> request, AccessExecutionJobVertex jobVertex) {
        return createSubtaskTimesInfo(jobVertex);
    }

    @Override
    public Collection<ArchivedJson> archiveJsonWithPath(AccessExecutionGraph graph)
            throws IOException {
        Collection<? extends AccessExecutionJobVertex> allVertices =
                graph.getAllVertices().values();
        List<ArchivedJson> archive = new ArrayList<>(allVertices.size());
        for (AccessExecutionJobVertex task : allVertices) {
            ResponseBody json = createSubtaskTimesInfo(task);
            String path =
                    getMessageHeaders()
                            .getTargetRestEndpointURL()
                            .replace(':' + JobIDPathParameter.KEY, graph.getJobID().toString())
                            .replace(
                                    ':' + JobVertexIdPathParameter.KEY,
                                    task.getJobVertexId().toString());
            archive.add(new ArchivedJson(path, json));
        }
        return archive;
    }

    private static SubtasksTimesInfo createSubtaskTimesInfo(AccessExecutionJobVertex jobVertex) {
        final String id = jobVertex.getJobVertexId().toString();
        final String name = jobVertex.getName();
        final long now = System.currentTimeMillis();
        final List<SubtasksTimesInfo.SubtaskTimeInfo> subtasks = new ArrayList<>();

        int num = 0;
        for (AccessExecutionVertex vertex : jobVertex.getTaskVertices()) {
            // Use one of the current execution attempts to represent the subtask, rather than
            // adding times info of all attempts.
            long[] timestamps = vertex.getCurrentExecutionAttempt().getStateTimestamps();
            ExecutionState status = vertex.getExecutionState();

            long scheduledTime = timestamps[ExecutionState.SCHEDULED.ordinal()];

            long start = scheduledTime > 0 ? scheduledTime : -1;
            long end = status.isTerminal() ? timestamps[status.ordinal()] : now;
            long duration = start >= 0 ? end - start : -1L;

            TaskManagerLocation location = vertex.getCurrentAssignedResourceLocation();
            String host = location == null ? "(unassigned)" : location.getHostname();
            String endpoint = location == null ? "(unassigned)" : location.getEndpoint();

            Map<ExecutionState, Long> timestampMap =
                    CollectionUtil.newHashMapWithExpectedSize(ExecutionState.values().length);
            for (ExecutionState state : ExecutionState.values()) {
                timestampMap.put(state, timestamps[state.ordinal()]);
            }

            subtasks.add(
                    new SubtasksTimesInfo.SubtaskTimeInfo(num++, endpoint, duration, timestampMap));
        }
        return new SubtasksTimesInfo(id, name, now, subtasks);
    }
}
